Pneumatic door check



Oct. 16, 1962 H. HARRISON ETA]. 3,

PNEUMATIC DOOR CHECK Filed Feb. 2, 1960 2 Sheets-Sheet 1 Fig l Fig. 2.Fig-3v INVENTORS HENQT Hmrzlsw HENRY C. Hmmgou BYMMQQMZZ7 W ATTORNEYSOct- 1 2 H. HARRISON ETAI.

PNEUMATIC DOOR CHECK 2 Sheets-Sheet 2 Filed Feb. 2, 1960 w o 6 m w 0 E m.m. WWW F. m m HC mm mm Hun Fig. 5 BYWQMfW ATTORNEYS 3,d58,146 PatentedOct. 16, 1962 3,058,146 PNEUMATIC DGDR QHECK Henry Harrison, R0. Box117, Locust Valley, N.Y., and

Henry C. Harrison, 94 Bayview Ave, Port Washington, N.Y.

Filed Feb. 2, 1960, Ser. No. 6,297 16 Claims. (Cl. 16-66) This inventionrelates to pneumatic door checks and means for coupling pneumatic doorchecks with a door and an associated door frame. More particularly, thisinvention relates to an improved pneumatic door check which incorporatesauxiliary means for allowing compressed gas to escape from the check ata pre-determined instant to assure proper closing of the door, and to animproved linkage between a door check and an associated door structure,which linkage allows for fully opening a door swingably mounted withrespect to a door frame.

Various types of pneumatic door checks have heretobeen suggested for usein controlling closing movement of a door. Generally, the priorconstructions provide a check cylinder with a piston reciprocallymounted therein. The cylinder is normally coupled to the door and thepiston is normally coupled to the associated door frame so that thepiston moves backward in the cylinder upon opening the door, and forwardin the cylinder upon closing the door. Some means is provided, either asa part of the check or separate therefrom, for urging the door to closedposition whereby once the door has been opened, it automatically swingstoward closed position. The piston and cylinder arrangement, under theaction of the means for urging the door closed, provides a compressedair cushion within the cylinder upon closing of the door whichsupposedly prevents the door from meeting the frame with a large impact.Normally, an adjustable outlet is also provided in the cylinder to allowair under compression to escape at a selected rate commensurate with theclosing force applied to the door. When such arrangement is utilized forcontrolling a door, proper closing is, at best, achieved only when thedoor is opened to a position within a pre-determined rather small rangeof positions. If the door is opened further than the maximum position inthe range to which the outlet has been adjusted, or not opened as far asthe minimum position of the range to which the outlet has been adjusted,then either: (a) the door closes so slowly that it fails to operate anassociated latch, locking device, or the like; or (b) the door swingsshut so quickly that there is a severe impact of the door upon itsframe; or (c) the door rebounds from a closing path of travel and thenmoves into the frame at an excessive speed. The adjustment of theoutletv is a compromise for a limited range of opening positions. Inaddition to the above disadvantages of prior art constructions, thelinkages heretofore suggested for coupling the door checks with the doorframes commonly prevented opening the door beyond a position where thedoor is at right angles to the frame. In those cases where a couplinglinkage permitting the door to open further is suggested, the structureof the linkage has been complicated or subject to buckling in improperdirections which would prevent efficient functioning of the door checkto which it was coupled.

Accordingly, primary objects of the present invention are: (a) toprovide an improved pneumatic door check which assures proper control ofdoor closing regardless of the position to which the door is opened, and(b) to provide an improved door check coupling which allows for openingthe door through 180 and which prevents improper pivotal movementbetween coupled components.

In particular, a primary object of the present invention is to providean improved pneumatic door check having a piston and cylinderarrangement as described above, and also incorporating valve meansresponsive to gas pressure within the housing, which valve means servesto relieve increased pressure at a pre-determined instant so as toassure proper closing of the door with which the check is used. Evenmore specifically, an object of this invention is to provide a doorcheck as prescribed above and incorporating automatically-operable valvemeans which acts to relieve increased pressure in the cylinder at apredetermined door speed, so as to assure proper closing of the doorwith which the check is used.

Another object of the invention is to provide a door check in accordancewith the preceding object, which check includes, as an integral partthereof, means for automatically urging the door to closed position,preferably in the form of a spring, and means for automatically takinginto account the force of the spring so as to substantially eliminateacceleration of the door after the desired speed of closing has beenreached, so that the door completes its closing at that predetermineddesired speed.

A still further, and more specific object of this invention is toprovide an improved door check as prescribed above, wherein theadditional valve means for releasing increased pressure within thehousing is carried within the door check and is operable upon selectedmovement between a piston of the check and a piston rod on which suchpiston is slidably mounted, which movement results from a change inpressure conditions within the housing.

Still another, and further object of the invention is to provide animproved door check in accordance with the preceding objects, whichcheck is capable of being easily and inexpensively fabricated, and whichcheck comprises relatively few components so as to assure extendedtrouble-free operation.

Another primary object of the present invention is to provide animproved door check coupling which allows for opening of an associateddoor through by pivota1 movement of coupled components, but whichincorporates means for preventing improper pivotal movement of coupledcomponents.

Still other specific objects of this invention with respect to theimproved coupling are: (1) to provide a pivotal link having across-member adapted to bear against an edge of the door during openingand closing thereof; (2) to provide as a part of the coupling, a bracketadapted to be attached to the door frame, which bracket carries frictionwashers and pivot points engageable by legs of the pivotal link; and (3)to provide a link and bracket as prescribed in sub-paragraphs (1) and(2), which allow for springing the link into pivoting position on thebracket so as to avoid the necessity of utilizing tools to couple thecomponents of the check together, or uncouple them. 7

Basically, and in its simplest aspects, the invention provides a doorcheck comprising a housing preferably having an adjustable orifice, apiston reciprocal within the housing, means for coupling the housing toone portion of a door-door frame structure, and means for coupling thepiston with the other portion of such structure, which componentsfunction to compress gas within the housing upon closing of the door. Avalve means responsive to a selected pressure condition within thehousing is incorporated as part of the check, and this valvemeans servesto relieve pressure Within the housing at a pre-determined door speed.The improved meansprovided by the invention for coupling the piston withthe door structure-preferably comprises a bracket and associated pivotallink, which link has spaced apart arms adapted to be pivotally coupledwith the bracket, and a cross-member carried between the arms whichbears against a door edge during wide opening and clos- 3 ing operationsand prevents improper pivoting between the link and a coupled pistonrod.

The invention will be better understood, and objects other than thosespecifically set forth will become apparent, when consideration is givento the following detailed description of the exemplary embodiments ofthe invention. The description refers to the annexed drawings, wherein:

FIGURE 1 is a plan view of a door-door frame structure provided with theimproved door check and door check coupling provided by this invention,and presents the door and check components in partially opened position;

FIGURE 2 is a plan view similar to FIGURE 1, but presents the door infully opened position, and shows the disposition of check componentsunder such condition;

FIGURE 3 is also a plan view similar to FIGURE 1, however, FIGURE 3shows the door in closed position and the associated closed position ofcheck components;

FIGURE 4 is a detailed fragmental view showing the operativerelationship between (a) the coupling bracket, coupling link, and checkpiston rod constructed in accordance with the preferred embodiment ofthe invention, and (b) the associated components of the doordoor framestructure;

FIGURE 5 is a cross-sectional view of the improved door check providedby this invention, and presents the components thereof in the positionoccupied when the door to which the check is coupled is fully closed;

FIGURE 6 is a plan view, partially in section and similar to FIGURE 5,however, FIGURE 6 presents the components of the check in one of thepositions they occupy when the door is moving from an open to a closedlocation;

FIGURE 7 is a detailed view of the valve means provided by thisinvention for releasing compressed gas from the check, and shows theposition of the components of such valve means when it is open;

FIGURE 8 is a detailed fragmental view of the bracket and one end of alink which are parts of the improved coupling provided by the invention;

FIGURE 9 is a perspective view of a preferred form of link memberprovided by the invention;

FIGURE 10 is a plan view of a preferred form of washer utilized in theauxiliary valve means provided in accordance with the invention; and

FIGURE 11 is a perspective view of a preferred type of valve plugutilized in the auxiliary valve means of the invention.

Referring more particularly to the drawings, in FIGURE 1 the numeral 2designates a door frame and the numeral 4 designates a door swingablymounted with respect to frame 2 by means of hinges such as thatdesignated by numeral 66. The door 4 is movable from the fully closedposition shown in FIGURE 3 to the fully open position shown in FIGURE 2.

Coupled between the door frame 2 and the door 4 is a door check device 8comprising a check cylinder or housing 10 pivotally coupled with door 4by means of hinge 18 and having a reciprocal check cylinder rod 12extending beyond one end of the housing. The device also has a couplinglinkage 14 and bracket 16 connecting the rod 12 with the frame 2. As isapparent from FIGURES l, 2 and '3, the check cylinder rod 12 moves intothe housing as door 4 closes in on frame 2, and moves out of the housingas door 4 is moved to its open position. The coupling linkage 14 andassociated bracket 16, and housing bracket 18 serve as means tooperatively mount the check for the prescribed reciprocation of rod 12,and will be described in detail hereinafter. The important factor tounderstand initially is that the rod 12 moves in and out of the housingcorresponding to closing and opening of the door respectively.

By referring to FIGURE 5, it will be seen that the rod 12 carries at itsforward end 12 a piston 20 which has secured thereon a leather seal cup22. The seal cup 22 has a skirt portion 24 which engages the side wallsof the cylindrical housing 10 and slides therealong when the piston ismoved within the housing 10. The detailed construction of pistoncomponents is explained more fully below, but it should be noted thatthe cup member 22 prevents gas from moving therepast rearwardly in thehousing. Thus forward movement of the piston, and thereby the cupmember, results in exerting a force on gas within the housing forward ofthe piston.

At the same time, it should be understood that withdrawal of the pistonwithin the housing causes a flow of air past the skirt portion 24 ofseal cup 22 into the space within the housing forward of the piston.

Communicating with the space between the piston and the forward end 10of the housing, is a valve means 26. This valve means is preferablycarried by the housin 10 at its forward end 10 and comprises a threadedaperture 28 and a screw 30 carrying threads cooperating with those onthe aperture and having a recess 32 therein. Recess 32 which may be inthe form of a slot, groove or diagonal hole extends through the threadedsurface of the shank of screw 3% so that gas can pass out from housing10 through the recess. Moreover, the size of the orifice defined byrecess 32 can be adjusted by turning screw 30 so that its threaded shankmoves into, or out from, the interior of housing 19.

While the door check provided by this invention can be operated with anyfluid, it is suitable for compressible fluids, particularly air, whichis preferred because sealing problems are avoided by using air.

In order to fully comprehend the invention, assume for the moment,contrary to the teachings of the invention, that the check plungermeans, or piston 20, is rigidly secured on rod 12. If this constructionis incorporated in a door check as described above, and such check iscoupled with a door frame structure as shown in FIGURES 1-3, and thedoor is moving from open to closed position under the action of someurging means, then as the door closes the space between piston 20 andthe forward wall 10' of the housing decreases. If the screw 30 isadjusted so that the air confined in such space can escape so rapidlythat there is no substantial compression thereof, then the door meetsthe frame with severe impact, since the urging means, which usuallytakes the form of a spring, continuously accelerates the door during itsclosing travel, since no force is exerted on the door, or within thecheck, in opposition to the accelerating force of the urging means. Onthe other hand, if screw 30 is adjusted so that air cannot escape fastenough when the piston moves forward, then air is compressed betweenpiston 20 and the forward end 10' of the housing, and such compressedair exerts a force opposing that exerted by the urging means. Assumingthe outlet through recess 32 is sufliciently large to preventcompression of the air to an extent where it rebounds due to its elasticqualities, the door will shut relatively smoothly. However, the rate ofcompression and thereby degree of compression of the air depends on theextent to which the door was opened, because under the action of urgingmeans, the velocity of closing of the door during compression depends onthe time during which it is accelerated by the urging means and therebythe degree to which the door was opened. Accordingly, if the outletthrough recess 32 is sufficiently large to prevent compression of air toan extent where it rebounds due to its elastic qualities, yetsufficiently small to allow for compression to a certain extent uponclosing of a door that has been opened to a given position, then thesame ad justment of the screw will not provide for proper escape andthereby proper limited compression when the door is opened to asubstantially different position because the escape rate of thecompressed air will have to be different. For example, if the door isopened further than the position to which screw 30 was adjusted, thenthe maximum closing velocity of the door during compression isincreased, and the rate of compression is increased. Thus for properclosing, the outlet through recess 32 should be larger than when thedoor was opened to the previous position in order to allow entrapped gasto escape at a rate which prevents rebounding due to the elasticproperties of the gas. However, the opening through recess 32 remainsthe same size, and thus the door will not properly shut regardless ofthe position to which it was opened.

Just as in the conventional door check action just described, a doorcheck constructed according to the present invention compresses air bythe closing action of the door, and exerts a reaction force against thedoor which opposes its closing motion. As long as the rate of closing ofthe door is high, the pressure of the entrapped air rises, and when thepressure gets sufficiently high, it slows the doors motion. However,eventually, as the door slows down, the rate of compression reaches apoint where it drops below the rate at which air is escaping through therecess 32, and the pressure of the entrapped air within the cylinderbegins to drop. For a given positioning of the orifice screw 30, thespeed of the door at this point is substantially independent of thepressure of the entrapped air, because the volume rate of flow of airthrough an orifice is nearly independent of the pressure. In contrast toconventional door checks, the door check of the present inventionprovides a control system which automatically detects the condition whenthe pressure begins to drop and opens a valve which releases theentrapped gas or air so that the door can coast shut at a predeterminedspeed corresponding to the setting of the orifice screw 30.

Attention is now directed to the construction of piston 20 and pistonrod 12. The control system or auxiliary valve means which releases theentrapped air in response to an incipient fall of pressure is preferablycarried by piston 20 and cooperates with piston rod 12 as hereinafterexplained. To fully comprehend the operation of the auxiliary valvemeans, a full understanding of the action of piston 20 in theconstruction illustrating this invention is helpful. Accordingly,attention is initially directed to the construction of piston 20 andpiston rod 12 in the following paragraphs.

According to the preferred embodiment of the invention, piston 20 is notrigidly secured on rod 12, but is slidably mounted thereon. The rod 12extends through a bore 34 in the piston, and abutment means 36,preferably in the form of an enlarged flared end, is provided on thepiston rod 12. The piston 20 is provided with an outward bevel 38 at theforward end of bore 34 and this bevel cooperates with the flare 36 onthe piston rod to prevent movement of the piston on the piston rodforwardly of the position shown in FIGURE 5. Spaced from the flare 36carried at the forward end 12 of the piston rod, is a snap ring 40 whichcooperates with a recess 42 in the rod. A washer 44 carried on rod 12 isdisposed forwardly of ring 40, and a spring 46 extends between washer 44and the circumferentially extending flange portion 21 of piston 20. Thespring 46 continuously urges piston 20 forward on rod 12, however, whena pressure is applied to piston 29 in the direction of arrow A, thepiston slides rearwardly on rod 12 and spring 46 is compressed as shownin FIGURE 6. Thus, it should be apparent that piston 20 is slidably orreciprocally mounted on rod 12, and that the piston can be displacedfrom its forward position on the rod when sufficient pressure is exertedon the piston to compress spring 46. As is evident from FIGURES 5' and6, ring 40 serves as an abutment or stop means for preventing rearwardmovement of washer 44 along piston 12 beyond the forward face of thering.

In addition to the spring 46, door checks constructed in accordance withthe preferred embodiment of this invention include a spring 50 extendingbetween washer 4 4 and the rearward end of housing 20. Spring 50 has alower coeflicient of compression than spring 46 so that when pressure isapplied to piston 2th in the direc- 6 tion of arrowA, washer 44 movesrearwardly and into engagement with ring 40 prior to the time thatspring 4 6 is compressed.

It should be understood, however, that any suitable means may be usedfor urging the door closed without departing from the scope and spiritof the invention. For example, a spring separate from the door check maybe coupled between the door and door frame to serve as the means forurging the door closed, and in such instance, the washer 44 mightcontinuously engage ring 40, and different provision might be made toreduce the acceleration of the door, after release of the entrapped air,as will be hereinafter explained. However, preferably the urging meansis an integral part of the check as presented in the drawings.

if the door check described above, and shown in FIG- URES 5 and 6, iscoupled with a door and associated door frame as shown in FIGURES 1through 3, then as the door is opened, piston rod 12 is drawnrearward-1y in housing 10. The flare 36 on end 12 of the piston rodengages the bevel 38 of piston 20 and piston 20 moves rearwardly withthe rod. Similarly, washer 4 4- which is held in spaced relation fromthe flange portion 21. of the piston by spring 46, moves rearwardly, andas a result spring 50 is compressed between the washer 44 and therearward end 10 of the housing. Preferably, the spring 50 is ofsuflicient size that it does not become fully compressed upon opening ofthe door to the maximum extent. Thus, spring 46 is not fully compressedduring the door opening operation.

Once the door has been opened and released, the means for urging thedoor closed, namely, spring 50, pushes washer 44 and thereby piston 20and rod 12 forward. This results in automatically moving the door toclosed position. The forward force applied to piston 20 and piston rod12, and through the coupling of housing 10, to the door, causesacceleration of the door as it moves to closed position. Thus, thepiston 20 and rod 12 move forward in housing 10 at an accelerated rate.If the screw 31} is adjusted such that the opening through recess 3-2 isnot suflicient to allow for escape of gas therefrom at a ratecorresponding to the closing speed of the door, then the pressure of aircompressed between piston 20 and the forward end 10' of housing 10increases to a point where it is sufficient to push piston 20 rearwardlyon rod 12 compressing spring 46. As soon as the door has been slowed tosuch a speed that the rate of escape of air is equal to the rate ofcompression, by the restraining force of the compressed gas in thehousing as exerted between the coupling of the housing with the door andthe coupling of the piston rod with the frame, the pressure of thecompressed gas begins to drop, and thus piston 20 moves forwardly on rod12.

As explained hereinbelow, the movement between the piston and the pistonrod described in the preceding paragraph is used, according to thepreferred embodiment of this invention, to operate the second orauxiliary valve means which releases the compressed gas as soon as thepiston begins to move forward on the piston rod. Obviously, the instantat which the piston begins to move forwardly with respect to the pistonrod is the instant at which the pressure of the entrapped gas begins tofall. As explained above, this instant corresponds to the time when thedoor has been slowed to a speed preselected by adjustment of the orifice26 in housing 10.

Thus, it should be apparent that when the forward movement of piston 20on rod 12 is utilized to open a valve, the compressed gas trapped in thehousing will be released at the proper instant to allow the door to shutat a preselected speed. According to the invention, the second orauxiliary valve means is operated by such movement of the piston, sothat the speed selected by adjusting screw 30 is the speed at which thedoor closes in upon its associated frame.

The auxiliary or second valve means which is responsive to a change inpressure within housing 10, or more specifically movement of the pistonon the piston rod, includes, as shown in FIGURES 5, 6 and 7, an orificemember 52 having an aperture 54 centrally disposed therein, a supportwasher 56, a resilient U-shaped member 58, and a plug member 60. FIGURESl and 11 present the preferred form of components 56 and 60 in detail.

As shown in FIGURES and 6, the orifice member 52 and support washer 56are carried in an enlarged bore 62 in piston 20. Bore 62 is axiallyaligned with, and extends forwardly of, bore 34 with which piston rod 12cooperates. The central portion of orifice member 52 is spaced from thecentral portion of support washer 56, and the outwardly flared ends 59,59' of resilient U- member 58 extend through the aperture 57 in supportwasher 56. Plug member 60 floats within the resilient U-shaped member53, and normally closes the aperture 54 in onifice member 52 because theflared ends 59, 59 of the resilient U-shaped member ride up within theaperture 57 in the washer 56. The flared ends 59, 59 of the U-shapedmember preferably make a angle with the respective legs of the U, andextend to a point slightly below the underside of orifice member 52 sothat there is some play between the tips of the ends and the undersideof the orifice member.

The body of U-shaped resilient member 58 has a lateral dimensionsubstantially equal to the diameter of a bore 70 centrally disposed inthe forward end 12' of the piston rod 12, so that the valve means 80functions as follows: when the piston 20 moves rearwardly on rod 12 tothe position shown in FIGURE 6, the legs of the resilient U-member 58frictionally engage the walls of bore 70 and the tips of the flared ends59, 59' contact the underside of the orifice member. As the piston movesrearwardly, the support washer 56 no longer engages the flared ends 59,59 of the resilient U-member 58, however, U-member 58 still retains theplug member 60 in closing engagement with the aperture 54- in orificemember 5 2 because of the frictional engagement of the legs of member 58in bore 70.

After the components have moved rearwardly under the increased pressure,the pressure drops, and forward movement results as explainedhereinabove. When piston 20 moves forwardly due to decrease in pressureof compressed gas, the resilient U'member 58 is frictionally engaged bythe walls of bore 76, and thus does not initially move forward with thepiston. The plug member 60 is freed of engagement with the aperture 52so as to provide an escape outlet. The trapped air rushes out throughthe aperture 54-, and through the loose sliding fit of the piston on therod. The effect of the escaping air is to move the piston still furtherforward, which opens the valve more and makes the escape of air morerapid. As should be apparent, the auxiliary valve means opens as soon asthe pressure of compressed gas decreases. Thus, the valve is responsiveto gas pressure within the housing, or a change thereof, so as to assureproper closing of the door. As should also be apparent, the opening ofthe valve is limited by the flared ends 59, 59 of the member 58, whichends engage the support washer 56. Thus, after releasing compressed gas,the valve closes as support washer 56 engages the flared ends 59, 59 ofresilient member 58 and carries the member forward free of bore 70. Thevalve means thus closes prior tofinal closing of the door and is incondition for subsequent operation upon again opening the door. Butequally important, is the fact that when the valve closes the rapid dropof air pressure ceases. This occurs when the pressure of entrapped airis approximately equal to the pressure exerted by the urging means, orspring 50, so that the force applied to the door for final closing issubstantially zero. Accordingly, after the valve is closed, the doorcoasts shut at substantially constant speed.

Although the specific details of the housing construction, and the meansby which the seal cup 22 is retained on the piston, form no part of theinstant invention, the preferred construction is presented in FIGURES 5and 6. The housing It) comprises a central tubular member 100, to whichare secured caps 102 and 164. Cap 102 has a crimp 106 in its skirtportion and cap 104 has a crimp 1118 in its skirt portion. These crimpscooperate with associated crimps 110 and 112 in opposite ends of tubularmember 108 to hold the caps in position at either end thereof. Cap 102carries the orifice means 26, and cap 16 has an aperture therein throughwhich piston rod 12 extends. The sealing relation between cap 102 andtubular member must be sufficient to prevent any substantial escape ofair, however, the sealing relationship between cap 164 and member 190can be loose.

The leather seal cup 22 is preferably retained on piston 28 by means ofan L-shaped cup retainer 116 which has internal fingers whichfrictionally grip the adjacent wall of piston 20, and a ring-shapedsurface bearing against a cup expander 118. The expander 118 serves tocontinuously press the skirt 24 of the cup outwardly and into engagementwith the side walls of the housing.

he means for coupling the piston rod 12 with the door frame as providedby this invention is shown in detail in FIGURES 4 and 8. The couplingmeans comprises a bracket 16 having a U-shaped central portion 168, fromwhich feet 162, 162 laterally extend. Apertures 163 are provided in thefeet to adapt the bracket for mounting on the frame by some suitablemeans such as screws 164-. A rivet shaft 166 projects from either leg ofthe U-shaped central portion 160 of the bracket, and friction washers168, 163 surround the associated ends of such shaft which projecttherebeyond. A pivotal link 170 which is preferably a tapered sheetmetal channel having legs 172, 172, and a cross-member 174, is pivotedabout bracket 16. The legs 172, 172 have apertures at either end thereofand are somewhat resilient. They are spaced apart so that one end of thelink can be sprung onto the bracket with the apertures therein engagingthe rivet 166 and the legs pressing against the friction washers 166,168'. The opposite end of link 170 is coupled with the free end ofpiston rod 12 by means of a suitable bolt 173 extending through theapertures in that end of the link, as well as a bore in piston rod 12spaced a short distance from the end of that rod.

The side of the link carrying cross-member 174 is tapered outwardly fromits connection with piston rod 12 to its connection with bracket 16, asshown in FIG- URE 4, and the cross-member 174 of the link has a flatface 176 which is disposed adjacent the end of the door hinged to theframe via hinges such as that designated by numeral 6.

As is apparent from FIGURE 4, the door 4 is swingable with "respect tothe door frame 2 about one edge 180 of the end 182 of the door. As thedoor opens, the link 170 acts first as a pure tension member. However,when the door approaches 90 open, the face 176 of crossmember 174 beginsto bear against the back edge of the door, and the piston rod begins toturn out of line with the link. As the door opens further, the linkcontinues to press and slide slowly on the back edge 184 of the door,and piston rod 12 pivots toward a right angle position with respect tolink 170. The force of spring 50 increases as the door opens, however,the lever arm through which such force acts decreases so that the torqueon the door stays within reasonable limits.

After the door is released and begins to swing shut, the piston rod 12pivots in the direction of arrow B, and eventually moves to a positionwhere the longitudinal axis of the link is aligned with the longitudinalaxis of the rod. The friction exerted on the link by the frictionwashers 168, 168' presses the rod 12 into engagement with thecross-member 174 which serves as a stop means preventing improperpivoting of rod 12 past the crossmember in the direction of the arrow B.Accordingly,

the friction washers at the bracket, and cross-member 174 coact tomaintain the rod in alignment with the link, and prevent buckling underthe compression load of checking the doors closing motion.

It should be apparent that the cross-member extends along the linkbetween arms 172 and 172' thereof a sufficient distance to prevent thefree end of piston rod 12 from swinging therepast in the direction ofarrow B, and that the spring clasping of the legs 172, 172 of the linkagainst the friction washers provides for smooth, noiselessfriction-resisting pivoting of the legs about the axis of the rivetshaft 166 carried by the bracket. Moreover, with such spring claspingarrangement, the link can easily be detached from the brackets in theevent it is desired to remove the door.

FIGURE 9 presents the link 14 in perspective, and by referring to thatfigure, it will be noted that the link is tapered outwardly from the endthereof adapted to cooperate with the piston rod to the end adapted toconnect with the jamb bracket.

After reading the foregoing description of the exemplary embodiments ofthe invention, the fact that the stated objects have been successfullyachieved should be apparent. Accordingly, I claim:

1. A door check for use with a door swingably mounted with respect to aframe therefor, comprising the combination of a housing, plunger meansfor compressing gas within said housing upon closing of said door, firstvalve means for allowing gas to at least leave said housing uponmovement of said plunger means, second valve means operative to remainclosed so long as gas pressure increases within said housing andindependent of the magnitude of absolute pressure therein, but operativeto open in response to a decreasing change in said housing pressure, andmeans for coupling said housing and said plunger with the door and the.door frame.

2. In a door check, the combination of a housing, plunger meansreciprocal within said housing for compressing gas within said housingupon closing of said door, first valve means for allowing gas to atleast leave said housing upon movement of said piston plunger means, andsecond valve means operative to remain closed so long as gas pressureincreases within said housing and independent of the magnitude ofabsolute pressure therein but operative to open in response to adecreasing change in gas pressure within said housing for releasing gasfrom said housing.

3. In a door check, the combination defined in claim 2 wherein saidplunger means comprises a piston rod, and a piston slidably coupledthereto, and wherein said second valve means is responsive to slidingmovement between said piston and said rod in a given direction.

4. In a door check adapted for use with a swingably mounted door, thecombination defined in claim 2 wherein said first valve means isadjustable and is carried by said housing, and wherein said second valvemeans is carried by said plunger means.

5. In a door check adapted for use with a door swingable between openand closed positions, the combination of a hollow housing, a pistonreciprocal within said housing in response to opening and closing of thedoor, said piston co-operating with said housing to compress gas in aportion of said housing upon closing of the door, first valve meanscommunicating with said portion of said housing for allowing gas toenter said portion of said housing upon opening of the door and forallowing gas to escape from said portion of said housing at a controlledrate upon closing of the door, and second valve means responsive to adecreasing change in pressure of compressed gas acting on said pistonupon closing of the door for allowing said compressed gas to escape fromsaid portion of said housing.

6. In a door check adapted for use with a door swingable between openand closed positions, the combination defined in claim 5 and furtherincluding a piston rod '10 for moving said piston in one direction uponopening of the door, and spring means carried within said housing forurging said piston in the opposite direction.

7. In a door check adapted for use with a door swingable between openand closed positions, the combination defined in claim 5 wherein saidfirst valve means is adjustable to control the size of an orificetherein through which gas enters and escapes from said portion of saidhousing.

8. In a door check adapted for use with a door swingable between openand closed positions, the combination defined in claim 5 wherein saidsecond valve means is carried by said piston.

9. In a .door check adapted for use with a door swingable between openand closed positions, the combination defined in claim 5 and furtherincluding a piston rod on which said piston is slidably engaged formoving said piston in one direction upon opening of the door, whereinsaid second valve means cooperates with said piston and said piston rodand is responsive to sliding movement of said piston on said piston rodin a direction opposite to said one direction.

10. In a door check adapted for use with a door swingable between openand closed positions, the combination defined in claim 5 and furtherincluding a piston rod for moving said piston in one direction uponopening of the door, and spring means carried within said housing forurging said piston in the opposite direction, wherein said first valvemeans is adjustable to control the size of an orifice through which gasenters and escapes from said portion of said housing, wherein saidpiston is slidably engaged on said piston rod, and wherein said secondvalve means cooperates with said piston and said piston rod and isresponsive to sliding movement of said piston on said piston rod in adirection opposite to said one direction.

11. A door check for use with a door swingable with respect to anassociated frame therefor, comprising a walled housing having a forwardend and a rearward end, a piston engaging the walls of said housing andbeing reciprocal between said forward end and said rearward end of saidhousing, a piston rod cooperating at one end with said piston forsliding movement of said pison on said rod, and having the other endextending through the rearward end of said housing, first abutment meanscarried by said piston rod at a point spaced from said one end thereof,means cooperating with said abutment means and said piston for urgingsaid piston toward said one end of said piston rod, second abutmentmeans carried by said piston rod at said one end thereof, said pistoncooperating with said second abutment means to prevent disengagement ofsaid piston from said piston rod at said one end, an adjustable valvecarried by said housing and communicating with the portion of saidhousing between said piston and said forward end of said housing,auxiliary valve means carried by said piston and cooperating with saidpiston rod for providing an outlet in the portion of said housingbetween said piston and said forward end of said housing in response tomovement of said piston on said piston rod toward said one end of saidpiston rod, and means for coupling said housing and said other end ofsaid piston rod with said door and the associated frame therefor.

12. A door check for use with a door swingable with respect to anassociated frame therefor as defined in claim 11 wherein said piston hasa portion thereof extending beyond said one end of said piston rod, saidportion of said piston having a first bore therein, wherein said pistonrod has a second bore therein aligned with the bore in said portion ofsaid piston, and wherein said valve means comprises an orifice memberhaving an aperture therein and disposed in said first bore, a supportwasher disposed in said first bore, at least the central portion of saidwasher being spaced from the central portion of said orifice member, aplug member adapted to open and close the aperture in said orificemember and extending through said support washer, and a resilientsubstantially U-shaped member having flared end-s disposed between saidorifice member and said support washer, said resilient member normallyurging said plug member into closing engagement with said aperture insaid orifice member, said resilient member being engageable by saidsecond bore when said piston slides on said piston rod away from saidone end of said piston rod whereby when said piston slides toward saidone end of said piston rod, said resilient member is frictionally heldin said second bore and said plug member opens said aperture in saidorifice member.

13. A connection between a door check having a reciprocal rod extendingtherefrom and an associated doordoor frame combination wherein the dooris swingable through 180 about one edge of an end thereof into and outof closed position with respect to the frame and wherein said door checkis coupled to said door; said connection comprising a bracket adapted tobe mounted on the door frame; a link having one end adapted to bepivotally coupled to said bracket for pivotal movement about an axisparallel to said one edge of said door and having the other end adaptedto be coupled to said rod; and a cross-member carried by said link andhaving an at least substantially fiat face disposed on the side of saidlink adjacent the frame, said cross-member extending a sufiicientdistance along said link to prevent pivotal movement of said piston rodpast said cross-member, and to bear against the edge of the end of thedoor opposite said one edge thereof when the door is moved from itsclosed position through an angle of more than 90.

14. A connection as defined in claim 13 wherein said link and saidcross-member are a single unit comprising a tapered U-member with thelegs of the U-member having apertures at their ends, and With the baseof the U-member set back from the ends of the legs thereof, wherein saidbracket carries friction Washers on opposite outer faces thereof and ashaft extending through and beyond said washers, wherein one end of eachof the legs of said U-member springingly engage said washers, and theapertures therein cooperate with said shaft for pivotal movement of saidU-member about said bracket, and wherein the other end of each of saidlegs is pivotally coupled with said rod.

15. In a door check assembly, the combination comprising a hollowcasing, a piston reciprocal Within said housing in response to openingand closing the door, said piston cooperating with said housing tocompress gas in a portion of said housing upon closing the door, firstvalve means communicating with said portion of said housing for allowinggas to enter said portion of said housing upon opening of the door andallowing gas to escape from said portion of said housing at a controlledrate upon closing of the door, second valve means responsive to adecrease in pressure of compressed gas acting on said piston uponclosing the door for allowing said compressed gas to escape from saidportion of said housing, means coupling said housing to the door, abracket for mounting on the door frame, a link having one end pivotallycoupled to said bracket for pivotal movement about the axis parallel toone edge of said door and the other end coupled to a piston rod operablysecured to said piston, a cross-member carried by said link and havingan at least substantially fiat face disposed on the side of said linkadjacent to the door frame, said crossmember extending a sufficientdistance along said link, to prevent pivotal movement of said piston rodpast said cross-member, and to bear against the edge of the end of thedoor opposite said one edge thereof when the door is moved from theclosed portion through an angle of more than whereby the door isswingable through 16. A door check for use with a door swingably mountedwith respect to a frame therefor, comprising the combination of ahousing, a piston reciprocally disposed within said housing forcompressing gas within said housing upon closing of said door and apiston rod cooperating with said piston, first valve means for allowinggas at least to leave said housing upon movement of said piston, secondvalve means responsive to a change in gas pressure within said housingfor releasing gas from said housing, means for coupling said housingwith said .door, and means for coupling said piston rod with said doorframe including a bracket adapted to be fastened to said door frame anda link pivotally coupled at one end to said bracket and pivotallycoupled at its other end to said piston rod, said link having a stopmeans for preventing pivotal movement of said piston rod with respect tosaid link in one direction.

References Cited in the file of this patent UNITED STATES PATENTS467,997 Schubert et al. Feb. 2, 1892 678,790 Nushawg et al. July 16,1901 1,963,687 Tappan June 9, 1934 1,966,956 Dunn July 17, 19342,153,833 Hartshorn Apr. 11, 1939 2,416,316 Hines Feb. 25, 19472,441,037 Sherrin May 4, 1948 2,453,956 Angell Nov. 16, 1948 2,783,774Kimble et al. Mar. 5, 1957 2,920,338 Falk Jan. 12, 1960

